1. Field of the Invention
This invention pertains to cameras and particularly pertains to single lens reflex cameras.
2. Description of the Prior Art
The best prior art known to me is a conventional, single lens reflex camera as shown in FIG. 1. The camera has a box 10, film 36 and a focal plane shutter 14 with rollers 16 and 18 for carrying and moving the focal plane shutter. A flop-up mirror 20 is hinged at its uppermost point 21 and has a focusing position 22 and a picture taking position 24. Lens 30 is mounted in barrel 34 which is slideably moveable for focusing. Diaphragm 32 is mounted in barrel 34 for adjusting the aperture. During the focusing period, light transmitted by lens 30 is reflected from mirror 20 and focused on ground glass 26. The condition of focus and the contents of the scene about to be photographed are observed on ground glass 26 through focusing hood 28. A pentaprism with focusing screen and an eyepiece could be substituted for ground glass 26 and focusing hood 28.
In cameras of the Graflex style, mirror 20 is spring-biased toward its picture taking position 24 and is held in the focusing position 22 by a catch (not shown). When the focus and composition of the picture is satisfactory to the photographer, she releases the catch, the mirror 20 rotates upward to position 24, at the same time releasing the focal plane shutter causing the spring rollers to wind the curtain and the slot embedded in the curtain past the film 36 making the exposure. The act of taking the picture blots out the scene to the photographer until he resets the mirror 20 to its focusing and composing position 22. In the more complex cameras such as the Nikon Model FE, a complex mechanism is provided which on release causes the mirror to rotate from focusing/composition position 22 to position 24, actuating the focal plane shutter and then immediately rotating the mirror 20 back to its composing focusing position 22. These complex and precisely timed actions of the mirror 20 are totally eliminated in my invention by the simple expedient of moving the focal plane shutter into the same plane occupied by mirror 20 in its focusing and composing position and silvering the side of the shutter facing lens 30.
Other prior art is exemplified by the Pentax Auto 110 and the Kodak 126 SLR cameras. Both of these are single lens reflex cameras having a swing-up mirror but no focal plane shutter. In both of these cameras, the swing-up mirror acts as the shutter by remaining in the "up" position for the required duration of the exposure.
FIG. 2 shows a side elevation view of the interior of this type of camera. The construction is like that of the prior art of FIG. 1 except there is no focal plane shutter 14 or rollers 16 and 18. Instead, there is a mechanism (not shown) which quickly moves mirror 20 from focusing position 22 to picture taking position 24; holding it there for the required or preset duration of the exposure, then returning the mirror 20 to the focusing position, thereby cutting off light flow to film 36, terminating the exposure.